File bugs here for general Firefox build system issues. This includes problems running `mach build`, `mach configure`, `mach package`, `mach artifact`, and other mach commands related to building Firefox. This component also tracks issues related to moz.build and make files.

Currently, when the backend creates the files it creates, it doesn't track what it created. If for some reason (configuration switch, moz.build change, etc.) some of those files are not created anymore, they are left in the objdir.

Created attachment 822368[details][diff][review]
Keep track of files generated by a build backend
The backend.RecursiveMakefile filename change is because as no moz.build is changed here, without a file name change, the list would not be filled until there is a moz.build change. (or a configuration change, or anything else touching backend files)
(And the .built filename doesn't really match the new purpose)